System and method for the placement of rank information in a physical uplink shared channel

ABSTRACT

A wireless communication network includes a plurality of base stations capable of wireless communication with a plurality of subscriber stations within a coverage area of the network. At least one of the plurality of base stations is capable of selecting up to four orthogonal frequency-division multiplexing (OFDM) symbols in a subframe of a physical uplink shared channel. The up to four OFDM symbols are selected starting from the bottom a resource grid of the physical uplink shared channel in a bottom-up manner, and one or more rank information (RI) coded bits are repeated in each of the selected up to four OFDM symbols.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

This application claims priority as a continuation of U.S. patentapplication Ser. No. 12/287,413 filed Oct. 9, 2008, now U.S. Pat. No.8,154,983, and to U.S. Provisional Patent Application Ser. No.61/064,764, filed Mar. 25, 2008, entitled “METHODS OF MULTIPLEXING DATAAND CONTROL IN UPLINK CHANNEL.” The content of the above-identifiedpatent documents is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present application relates generally to wireless communicationsand, more specifically, to the placement of rank information in aphysical uplink shared channel.

BACKGROUND OF THE INVENTION

With regard to the multiplexing of control information with data on aphysical uplink shared channel (PUSCH), it has been proposed to placethe ACK/NACK (A/N) resources next to the reference signal. The reportingof rank information (RI) and control information (for example, qualityinformation/precoding matrix index (CQI/PMI)) on a PUSCH, where RIinformation and control information are always reported in the samesubframe, has also been proposed. The reporting may be periodic oraperiodic, and the control is calculated assuming the simultaneouslyreported RI.

As shown in FIG. 3, the A/N resources 302 are punctured into the dataresources 304 from the bottom up and two symbols away from referencesignal sources 306. Control resources 308 are placed at the beginning ofthe data resources. The maximum number of resources available for A/Ninformation is four single carrier-frequency division multiple access(SC-FDMA) symbols.

Therefore, there is a need in the art for an improved system and methodfor reporting RI. In particular, there is a need for a technique thatallows RI to be reported in the data resources of a PUSCH.

SUMMARY OF THE INVENTION

A wireless communication network comprising a plurality of base stationscapable of wireless communication with a plurality of subscriberstations within a coverage area of the network, wherein at least one ofthe plurality of base stations is capable of selecting two or moreorthogonal frequency-division multiplexing (OFDM) symbols in a subframeof a physical uplink shared channel, the two or more OFDM symbols areselected starting from the bottom of the physical uplink shared channelin a bottom-up manner, and repeating one or more rank information (RI)coded bits in each of the selected two or more OFDM symbols.

A base station capable of wireless communication with a plurality ofsubscriber stations within a coverage area of a network, where the basestation is capable of puncturing one or more rank information (RI)resources into data resources of a physical uplink shared channel,wherein the one or more RI resources are punctured starting from thebottom of the physical uplink shared channel in a bottom-up manner.

A method of operating a base station comprising replacing two or moredata resources in a subframe of a physical uplink shared channel withone or more rank information (RI) resources, wherein the two or moredata resources are replaced starting from the bottom of the physicaluplink shared channel in a bottom-up manner and are separated from areference signal resource in the physical uplink shared channel by atleast one resource which does not contain the one or more RI resources.

Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, itmay be advantageous to set forth definitions of certain words andphrases used throughout this patent document: the terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation; the term “or,” is inclusive, meaning and/or; the phrases“associated with” and “associated therewith,” as well as derivativesthereof, may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like; and theterm “controller” means any device, system or part thereof that controlsat least one operation, such a device may be implemented in hardware,firmware or software, or some combination of at least two of the same.It should be noted that the functionality associated with any particularcontroller may be centralized or distributed, whether locally orremotely. Definitions for certain words and phrases are providedthroughout this patent document, those of ordinary skill in the artshould understand that in many, if not most instances, such definitionsapply to prior, as well as future uses of such defined words andphrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an exemplary wireless network that transmits ACK/NACKmessages in the uplink according to the principles of the presentdisclosure;

FIG. 2A is a high-level diagram of an OFDMA transmitter according to oneembodiment of the present disclosure;

FIG. 2B is a high-level diagram of an OFDMA receiver according to oneembodiment of the present disclosure;

FIG. 3 illustrates a multiplexing of control resources, data resources,and ACK/NACK resources on a physical uplink shared channel (PUSCH);

FIG. 4 illustrates the placement of rank information (RI) in a PUSCHaccording to a first embodiment the present disclosure;

FIG. 5 illustrates the placement of RI in a PUSCH according to a secondembodiment the present disclosure;

FIG. 6 illustrates the placement of RI in a PUSCH according to a thirdembodiment the present disclosure;

FIG. 7 illustrates the placement of RI in a PUSCH according to a fourthembodiment the present disclosure; and

FIG. 8 illustrates a method of placing RI in a PUSCH according to anembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 8, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged wireless communication system.

With regard to the following description, it is noted that the LTE term“node B” is another term for “base station” used below. Also, the LTEterm “user equipment” or “UE” is another term for “subscriber station”used below.

FIG. 1 illustrates exemplary wireless network 100, which transmitsACK/NACK messages according to the principles of the present disclosure.In the illustrated embodiment, wireless network 100 includes basestation (BS) 101, base station (BS) 102, base station (BS) 103, andother similar base stations (not shown). Base station 101 is incommunication with base station 102 and base station 103. Base station101 is also in communication with Internet 130 or a similar IP-basednetwork (not shown).

Base station 102 provides wireless broadband access (via base station101) to Internet 130 to a first plurality of subscriber stations withincoverage area 120 of base station 102. The first plurality of subscriberstations includes subscriber station 111, which may be located in asmall business (SB), subscriber station 112, which may be located in anenterprise (E), subscriber station 113, which may be located in a WiFihotspot (HS), subscriber station 114, which may be located in a firstresidence (R), subscriber station 115, which may be located in a secondresidence (R), and subscriber station 116, which may be a mobile device(M), such as a cell phone, a wireless laptop, a wireless PDA, or thelike.

Base station 103 provides wireless broadband access (via base station101) to Internet 130 to a second plurality of subscriber stations withincoverage area 125 of base station 103. The second plurality ofsubscriber stations includes subscriber station 115 and subscriberstation 116. In an exemplary embodiment, base stations 101-103 maycommunicate with each other and with subscriber stations 111-116 usingOFDM or OFDMA techniques.

Base station 101 may be in communication with either a greater number ora lesser number of base stations. Furthermore, while only six subscriberstations are depicted in FIG. 1, it is understood that wireless network100 may provide wireless broadband access to additional subscriberstations. It is noted that subscriber station 115 and subscriber station116 are located on the edges of both coverage area 120 and coverage area125. Subscriber station 115 and subscriber station 116 each communicatewith both base station 102 and base station 103 and may be said to beoperating in handoff mode, as known to those of skill in the art.

Subscriber stations 111-116 may access voice, data, video, videoconferencing, and/or other broadband services via Internet 130. In anexemplary embodiment, one or more of subscriber stations 111-116 may beassociated with an access point (AP) of a WiFi WLAN. Subscriber station116 may be any of a number of mobile devices, including awireless-enabled laptop computer, personal data assistant, notebook,handheld device, or other wireless-enabled device. Subscriber stations114 and 115 may be, for example, a wireless-enabled personal computer(PC), a laptop computer, a gateway, or another device.

FIG. 2A is a high-level diagram of an orthogonal frequency divisionmultiple access (OFDMA) transmit path. FIG. 2B is a high-level diagramof an orthogonal frequency division multiple access (OFDMA) receivepath. In FIGS. 2A and 2B, the OFDMA transmit path is implemented in basestation (BS) 102 and the OFDMA receive path is implemented in subscriberstation (SS) 116 for the purposes of illustration and explanation only.However, it will be understood by those skilled in the art that theOFDMA receive path may also be implemented in BS 102 and the OFDMAtransmit path may be implemented in SS 116.

The transmit path in BS 102 comprises channel coding and modulationblock 205, serial-to-parallel (S-to-P) block 210, Size N Inverse FastFourier Transform (IFFT) block 215, parallel-to-serial (P-to-S) block220, add cyclic prefix block 225, up-converter (UC) 230. The receivepath in SS 116 comprises down-converter (DC) 255, remove cyclic prefixblock 260, serial-to-parallel (S-to-P) block 265, Size N Fast FourierTransform (FFT) block 270, parallel-to-serial (P-to-S) block 275,channel decoding and demodulation block 280.

At least some of the components in FIGS. 2A and 2B may be implemented insoftware while other components may be implemented by configurablehardware or a mixture of software and configurable hardware. Inparticular, it is noted that the FFT blocks and the IFFT blocksdescribed in this disclosure document may be implemented as configurablesoftware algorithms, where the value of Size N may be modified accordingto the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and should not beconstrued to limit the scope of the disclosure. It will be appreciatedthat in an alternate embodiment of the disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by Discrete Fourier Transform (DFT) functions andInverse Discrete Fourier Transform (IDFT) functions, respectively. Itwill be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 2, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In BS 102, channel coding and modulation block 205 receives a set ofinformation bits, applies coding (e.g., Turbo coding) and modulates(e.g., QPSK, QAM) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 210converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and SS 116. Size N IFFT block 215 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 220 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 215 toproduce a serial time-domain signal. Add cyclic prefix block 225 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter230 modulates (i.e., up-converts) the output of add cyclic prefix block225 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at SS 116 after passing through thewireless channel and reverse operations to those at BS 102 areperformed. Down-converter 255 down-converts the received signal tobaseband frequency and remove cyclic prefix block 260 removes the cyclicprefix to produce the serial time-domain baseband signal.Serial-to-parallel block 265 converts the time-domain baseband signal toparallel time domain signals. Size N FFT block 270 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 275 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 280 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of base stations 101-103 may implement a transmit path that isanalogous to transmitting in the downlink to subscriber stations 111-116and may implement a receive path that is analogous to receiving in theuplink from subscriber stations 111-116. Similarly, each one ofsubscriber stations 111-116 may implement a transmit path correspondingto the architecture for transmitting in the uplink to base stations101-103 and may implement a receive path corresponding to thearchitecture for receiving in the downlink from base stations 101-103.

The present disclosure describes a method and system for placing rankinformation in a physical uplink shared channel (PUSCH).

FIG. 4 illustrates the placement of rank information (RI) in a physicaluplink shared channel (PUSCH) according to a first embodiment thepresent disclosure. In this embodiment, RI coded bits 402 are repeatedtwo or more times in one subframe starting from the bottom up. RI codedbits 402 are placed such that RI coded bits 402 are separated fromreference signals 404 by at least one SC-FDMA symbol. In this particularexample, RI coded bits 402 are repeated four times in four OFDM symbolsand are placed two symbols away from reference signals 404. A/N bits406, data bits 408, and control bits 410 also are shown.

FIG. 5 illustrates the placement of RI in a PUSCH according to a secondembodiment the present disclosure. In this embodiment, RI coded bits 402are placed starting from the top down. In this particular example, RIcoded bits 402 are repeated four times in four OFDM symbols in onesubframe and are placed two symbols away from reference signals 404.

According to a third embodiment of the present disclosure, the RI bitsare jointly coded with the control bits. The control bits may includeCQI and PMI. In this embodiment, rank bits [o₀ ^(RI)] or [o₁ ^(RI), o₀^(RI)] are first coded using a subcode before being jointly coded withthe control bits o₀, o₁, o₂, . . . o_(o-1) into Q coded bits.

According to one example of this embodiment (assuming the number ofcoded bits after the RI sub-code is Q_(Ri)), if there is only one rankbit, denoted by o₀ ^(RI), then the one rank bit is repeated Q_(RI) timesto form the codeword.

If there are two rank bits (denoted by [o₁ ^(RI)o₀ ^(RI)], twoapproaches may be used. With the first approach, the two rank bits aresimply repeated └Q_(RI)/2┘ times to form the codeword if Q_(RI) is aneven number. For example, if Q_(RI)=4, the codeword is given by [o₁^(RI)o₀ ^(RI)o₁ ^(RI)o₀ ^(RI)]. If Q_(RI) is not an even number, thecodeword is concatenated with o₁ ^(RI) or o₀ ^(RI).

With the second approach, to form the coded bits for the two rank bits[o₁ ^(RI)o₀ ^(RI)], the two rank bits are mapped to a 3-bit codewordaccording to the simplex (3,2) code shown in Table 1 below.

TABLE 1 component simplex (3,2) code used for two rank bits. Twoinformation bits Component codeword c₁c₂c₃ (either A/N bits or rankbits) (Simplex (3,2) codebook) 00 000 01 011 10 101 11 110

The codeword is repeated └_(RI)/3┘ times, and the resulting sequence isconcatenated with the first Q_(RI)−3*└Q_(RI)/2┘ bits in the codewordc₁c₂c₃. This concatenated bit sequence is the final coded bit sequenceto be modulated and mapped into the channel sequence.

FIG. 6 illustrates an example of the placement of RI in a PUSCHaccording to the third embodiment of the present disclosure. In thisembodiment, resources 602 contain jointly coded RI bits and control bitssuch as CQI and PMI.

According to a fourth embodiment of the present disclosure, the RI bitsare jointly coded with ACK/NACK (A/N) bits using a linear block code.The joint coding block takes rank bit(s) [o₀ ^(RI)] or [o₁ ^(RI), o₀^(RI)] together with A/N bit(s) [o₀ ^(ACK)] or [o₁ ^(ACK)o₀ ^(ACK)] asinput and produces output bits [q₀ ^(A+R), q₁ ^(A+R), . . . q_(Q) _(A+R)^(A+R)]. In one embodiment, if there are no A/N bits to be transmittedin a given subframe, the UE sends a default value of (NACK) in the caseof one A/N bit and (NACK, NACK) in the case of two A/N bits.

FIG. 7 illustrates an example of the placement of RI in a PUSCHaccording to the fourth embodiment of the present disclosure. Resources702 contain jointly coded RI bits and A/N bits and are repeated fourtimes in eight OFDM symbols. In this particular example, each repetitionis placed on the symbols next to the reference signal symbols startingfrom the bottom up.

FIG. 8 illustrates a method of placing rank information (RI) in aphysical uplink shared channel (PUSCH) according to an embodiment of thepresent disclosure. In step 802, a base station or Node-B selects two ormore OFDM symbols in one subframe of a PUSCH starting from the last row(or subcarrier). The base station selects symbols that separated fromany reference signals in the PUSCH by at least one OFDMA symbol notcontaining RI coded bits. In step 804, the base station repeats orpunctures RI coded bits in each of the selected two or more OFDMsymbols. For example, the RI coded bits may be repeated or puncturedfour times in four OFDM symbols in one subframe and placed two symbolsaway from any reference signals as illustrated in FIG. 4. In otherembodiments, step 804 would involve replacing two or more data resourcesin the two or more OFDM symbols with the RI coded bits.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

1. A method in a base station for receiving control information and userdata in a communication system, the method comprising: receiving asubframe of a physical uplink shared channel, the subframe comprisingtwo slots, each slot comprising a reference signal; determiningmodulated encoded rank information and at least one modulated encodeduplink (UL) data from the received subframe, wherein the modulatedencoded rank information is mapped from a Single Carrier FrequencyDivision Multiplexing Access (SC-FDMA) symbol that is separated from thereference signal by at least one symbol; and demodulating encoded rankinformation bits and encoded UL data from the modulated encoded rankinformation and the at least one modulated encoded UL data based on acorresponding modulation scheme, wherein when the rank informationcomprises two rank information bits, the two rank information bits areencoded according to a repeated simplex (3,2) code.
 2. The method ofclaim 1, wherein the two rank information bits are mapped to a three-bitcodeword.
 3. The method of claim 2, wherein the three-bit codeword isrepeated to form a repeated three-bit codeword.
 4. The method of claim3, wherein at least a portion of the three-bit codeword is concatenatedwith the repeated three-bit codeword.
 5. The method of claim 1, whereindetermining the modulated rank information comprises: determining themodulated rank information from at most four selected SC-FDMA symbolswithin the subframe.
 6. The method of claim 5, wherein the at most fourSC-FDMA symbols correspond to up to four of the second, fifth, eighth,and eleventh symbols of the subframe.
 7. The method of claim 5, whereineach of the at most four SC-FDMA symbols is separated from a referencesignal by one symbol.
 8. An apparatus of a base station for receivingcontrol information and user data in a communication system, theapparatus comprising: a receiver configured to receive a subframe of aphysical uplink-shared channel, the subframe comprising two slots, eachslot comprising a reference signal; and a channel decoding anddemodulation block configured to: determine modulated encoded rankinformation and at least one modulated encoded uplink (UL) data from thereceived subframe, wherein the modulated encoded rank information ismapped from a Single Carrier Frequency Division Multiplexing Access(SC-FDMA) symbol that is separated from the reference signal by at leastone symbol, and demodulate encoded rank information bits and encoded ULdata from the modulated encoded rank information and the at least onemodulated encoded UL data based on a corresponding modulation scheme,wherein when the rank information comprises two rank information bits,the two rank information bits are encoded according to a repeatedsimplex (3,2) code.
 9. The apparatus of claim 8, wherein the two rankinformation bits are mapped to a three-bit codeword.
 10. The apparatusof claim 9, wherein the three-bit codeword is repeated to form arepeated three-bit codeword.
 11. The apparatus of claim 10, wherein atleast a portion of the three-bit codeword is concatenated with therepeated three-bit codeword.
 12. The apparatus of claim 8, wherein thechannel decoding and demodulation block is configured to determine themodulated rank information by determining the modulated rank informationfrom at most four SC-FDMA symbols selected in the subframe.
 13. Theapparatus of claim 12, wherein the at most four SC-FDMA symbolscorrespond to up to four of the second, fifth, eighth, and eleventhsymbols of the subframe.
 14. The apparatus of claim 12, wherein each ofthe at most four SC-FDMA symbols is separated from a reference signal byone symbol.
 15. A system for communicating control information and userdata, the system comprising: a user equipment (UE); and a base stationconfigured to: receive a subframe of a physical uplink shared channel,the subframe comprising two slots, each slot comprising a referencesignal, determine modulated encoded rank information and at least onemodulated encoded uplink (UL) data from the received subframe, whereinthe modulated encoded rank information is mapped from a Single CarrierFrequency Division Multiplexing Access (SC-FDMA) symbol that isseparated from the reference signal by at least one symbol, anddemodulate encoded rank information bits and encoded UL data from themodulated encoded rank information and the at least one modulatedencoded UL data based on a corresponding modulation scheme, wherein whenthe rank information comprises two rank information bits, the two rankinformation bits are encoded according to a repeated simplex (3,2) code.16. The system of claim 15, wherein the two rank information bits aremapped to a three-bit codeword.
 17. The system of claim 16, wherein thethree-bit codeword is repeated to form a repeated three-bit codeword.18. The system of claim 17, wherein at least a portion of the three-bitcodeword is concatenated with the repeated three-bit codeword.
 19. Thesystem of claim 15, wherein the base station is configured to determinethe modulated rank information by determining the modulated rankinformation from at most four SC-FDMA symbols selected in the subframe.20. The system of claim 19, wherein the at most four SC-FDMA symbolscorrespond to up to four of the second, fifth, eighth, and eleventhsymbols of the subframe.